The present invention relates to devices for administering, injecting, infusing, delivering or dispensing a substance or product, and to methods of making and using such devices. More particularly, it relates to a device for administering a substance, e.g. an injection device or an injection pen, which has a dose setting or selecting element for administering a set dose of an injectable product. In some embodiments, the injection device may be used for self-administering the product, e.g. in the form of a disposable injector, and may be used with a single-chamber or two-chamber ampoule.
Injection pens are widely used due to their size and shape, which makes them easy to handle when self-administering medicaments. Particularly if self-administering a medicament, such as insulin or a hormone, ease of handling, accuracy of the set dose and safety when setting the dose are of major importance.
Patent specification DE 10 2004 004 310, filed by the owner of the present application, discloses an injection device with a dose setting element, which effects a forward driving movement relative to the housing of the injection device in a forward drive direction and a dose setting movement in the direction opposite the forward driving movement and is coupled with a conveying mechanism so that the forward driving movement causes a conveying movement of the conveying mechanism, and the length of a distance defining the dose to be dispensed which is travelled by the dose setting element during the forward driving movement is set by the dose setting movement. A first catch mechanism is formed by the housing in a sleeve portion surrounding by the dose setting element and a second catch mechanism is formed by the dose setting element or a separate, additional dose setting catch body, and a catch engagement of the catch mechanisms can be released by a dose setting movement of the dose setting element or the separate, additional dose setting catch body without involving a rotating movement.
U.S. Pat. No. 5,807,346 discloses a measuring instrument for dispensing different doses of a liquid, which has a reservoir for accommodating the liquid, a displaceable toothed rack element axially disposed inside and a pushing element which can be operated by the user. Annular notches are provided on the toothed rack element and the housing has various axial slots distributed across its periphery. An outwardly projecting pin is provided on the pushing element, which is able to locate in one of the axial slots of the housing, and the setting element can be easily extracted by the user.
Patent specification EP 0 713 403 B1 discloses a syringe with a barrel, which defines or has a cylinder, the cylinder having a nozzle at one end and enclosing a plunger which is able to slide in the longitudinal direction inside the cylinder. The distance by which the plunger is able to move inside the cylinder defines the volume administered by the syringe, and the plunger is drivingly coupled with a slide which is disposed so that it moves parallel with the plunger, and the distance in length by which the plunger is able to slide inside the cylinder is defined by the movement restrictions of a stop surface on the barrel or the slide by reference to end stops on the slide or barrel. The syringe can be locked in a state in which the stop surface and the end stops are able to move only within movement limits with respect to one another, which can be selected from two or more pre-selectable predefined movement limits, and the stop surface has an insert which can be inserted from an orifice in the barrel or slide so that it projects out from it and is difficult to remove from them or can be so only by using a special tool, and the projecting part of the insert acts as a stop surface, and the position of each such orifice relative to the end stops defines one of the predefined movement distances.